TOKYO, Oct. 17 (Xinhua) -- An Air Self-Defense Force (ASDF) helicopter is believed to have crashed in the sea off Hamamatsu of Shizuoka prefecture, central Japan, Japanese Defense Minister Itsunori Onodera said on Tuesday.
The UH-60J helicopter belonging to the ASDF Hamamatsu base disappeared from radar some 30 km south of the base around 6:00 p.m. local time (0900 GMT).
What seemed to be parts of the chopper, including a door bearing the Air Self-Defense Force letters, have been found floating on the sea in that area.
"We cannot help but believe that the chopper has crashed," said Onodera.
Four people were onboard the chopper which was conducting a nighttime search-and-rescue drill when the incident happened.
The SDF has sent helicopters and vessels to search for the missing crew members.